Method and system of wireless power transfer foreign object detection

ABSTRACT

A wireless power transfer foreign object detector having at least one foreign object detector providing at least one foreign object detection signal, and at least one primary transmitter coil providing at least one primary transmitter signal, the primary transmitter coil responsive to the at least one foreign object detection signal.

PRIORITY ENTITLEMENT

This application is entitled to priority based on Provisional PatentApplication Ser. No. 61/592,481 filed on Jan. 30, 2012, which isincorporated herein by this reference. This application and theProvisional Patent Application have at least one common inventor.

TECHNICAL FIELD

The disclosure relates to wireless power transfer systems and the moresafe and efficient transfer of energy. More particularly, the disclosurerelates to foreign object detection using sensors in wireless power anddata transfer applications.

BACKGROUND

Wireless power transfer systems transfer electrical energy from onecircuit to an adjacent circuit. Wireless power transfer systems may beused to supply power, charge batteries, transfer data and the like. Onemethod of wireless power transfer is to utilize a variable current on aprimary transmitter coil to create a varying magnetic field and avoltage, in a secondary receiver coil. The primary transmitter coil isresponsive to a transmitting device that is transmitting energy. Areceiving device is responsive to the secondary receiver coil that isreceiving at least part of the transmitted energy. In another example ofthe disclosure the primary transmitter coil is coupled to a transmittermat. The secondary receiving coil is placed adjacent to the transmittermat and the secondary receiver coil electrically couples to the primarytransmitter coil.

Power transfer is intended to occur between the transmitting device andthe receiving device. Foreign objects receiving a portion of thistransmitted energy decrease the system efficiency. These foreign objectsmay provide a path where eddy currents may be generated causingelectrically induced thermal dissipation. During wireless powertransfer, ohmic losses may be incurred in addition to magnetic fieldlosses thereby increasing the difficulty in determining whether thetransmitting device is communicating solely with the receiving device orthe receiving device in addition to a foreign object. Variations inplacement of the primary transmitter coil and the secondary receivercoil may decrease the efficiency of the magnetic field coupling, andthus the system efficiency. The foregoing may thus increase the generaldifficulty in determining whether a system is transferring electricalenergy to energy dissipating foreign objects. Due to these and otherproblems and potential problems, improved detection of foreign objectsusing sensors would be useful and advantageous contributions to thearts.

SUMMARY

In carrying out the principles of the present disclosure, the device andmethod provides advances in the arts with apparatus and method directedto the transfer of power and/or data utilizing foreign object detection.In other examples, systems and methods include capabilities for powerand/or data transfer.

According to aspects of the disclosure, examples include a wirelesspower transfer foreign object detector comprising, at least one foreignobject detector providing at least one foreign object detection signaland at least one primary transmitter coil providing at least one primarytransmitter signal. The primary transmitter coil is responsive to the atleast one foreign object detection signal.

A further example would comprise a wireless power transfer foreignobject detector comprising, a transmitter mat, at least one foreignobject detector coupled to the transmitter mat, the at least one foreignobject detector providing at least one foreign object detection signal,at least one primary transmitter coil coupled to the transmitter mat.The at least one primary transmitter coil provides at least one primarytransmitter signal. The primary transmitter coil is responsive to the atleast one foreign object detection signal. At least one secondaryreceiver coil is electronically responsive to the at least one primarytransmitter coil. The at least one secondary receiver coil provides atleast secondary receiver signal. The at least one foreign objectdetector senses at least one magnetic or electric field characteristicof the at least one secondary receiver coil.

Another example would comprise a wireless power transfer foreign objectdetector comprising, a transmitter mat, at least one foreign objectdetector connected to the mat and providing at least one foreign objectdetection signal upon interaction with at least one foreign object. Theat least one foreign object detector senses at least one of a physicalinteraction with the at least one foreign object and an electricalinteraction with the at least one foreign object. At least one primarytransmitter coil provides at least one primary transmitter signal, theprimary transmitter coil is responsive to the at least one foreignobject detection signal.

An alternate example would comprise a method of wireless power transferforeign object detection comprising the steps of, detecting at least oneof a physical interaction with at least one foreign object and anelectrical interaction with the at least one foreign object andproviding at least one foreign object detection signal. The methodcomprises the step of modulating at least one primary transmitter signalin response to the at least one foreign object detection signal, whereinthe modulation comprises at least one of reducing the at least oneprimary transmitter signal and redirecting the at least one primarytransmitter signal in response to the at least one foreign objectdetection signal.

A further example would comprise a method of wireless power transferforeign object detection comprising the steps of, detecting at least onemagnetic or electric field characteristic, comparing the detected atleast one magnetic or electric field characteristic to a magnetic orelectric field characteristic look up table. The method furthercomprises modulating at least one primary transmitter signal in responseto the compared characteristic, wherein the modulation comprises atleast one of reducing the at least one primary transmitter signal andredirecting the at least one primary transmitter signal in response tothe at least one magnetic or electric field characteristic.

The disclosure has advantages which are not limited to one or more of,improved coupled inductor system power transfer and improved datatransmission functionality. These and other potential advantageous,features, and benefits of the present disclosure can be understood byone skilled in the arts upon careful consideration of the detaileddescription of representative examples of the disclosure in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be more clearly understood fromconsideration of the following detailed description and drawings inwhich:

FIG. 1 shows an example of a prior art wireless power transferschematic;

FIG. 2 shows a wireless power transfer foreign object detector having aprimary transmitter coil;

FIG. 3 shows a wireless power transfer foreign object detector having aprimary transmitter coil, the foreign object sensor embedded in thetransmitter mat;

FIG. 4 shows a wireless power transfer foreign object detector having aprimary transmitter coil and a transmitter mat with multiple foreignobject sensors;

FIG. 5 shows a wireless power transfer foreign object detector havingmultiple primary transmitter coils embedded in the transmitter mat;

FIG. 6 shows a wireless power transfer foreign object detector havingmultiple primary transmitter coils and multiple foreign object sensorsembedded in the transmitter mat;

FIG. 7 shows and describes a method of wireless power transfer foreignobject detection utilizing foreign object sensors; and

FIG. 8 shows and describes a method of wireless power transfer foreignobject detection utilizing sensing magnetic field.

References in the detailed description correspond to like references inthe various drawings unless otherwise noted. Descriptive and directionalterms used in the written description such as right, left, back, top,bottom, upper, side, et cetera, refer to the drawings themselves as laidout on the paper and not to physical limitations of the disclosureunless specifically noted. The drawings are not to scale, and somefeatures of examples shown and discussed are simplified or amplified forillustrating principles and features as well as advantages of thedisclosure.

DETAILED DESCRIPTION

The features and other details of the disclosure will now be moreparticularly described with reference to the accompanying drawings, inwhich various illustrative examples of the disclosed subject matter areshown and/or described. It will be understood that particular examplesdescribed herein are shown by way of illustration and not as limitationsof the disclosure. The disclosed subject matter should not be construeda limited to any of examples set forth herein. These examples areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the disclosed subject matter to those skilledin the art. The principle features of this disclosure can be employed invarious examples without departing from the scope of the disclosure.Patent applications and patents referenced herein are incorporated byreference.

The terminology used herein is for the purpose of describing particularexamples and is not intended to be limiting of the disclosed subjectmatter. Like numbers refer to like elements throughout. As used hereinthe term “and/or” includes any and all combinations of one or more ofthe associated listed items. Also, as used herein, the singular forms“a”, “an”, and “the” are intended to include the plural forms as well,unless the context clearly indicates otherwise. It will be furtherunderstood that the terms “comprises”, and/or “comprising” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof. Also, as usedherein, relational terms such as first and second, top and bottom, leftand right, and the like may be used solely to distinguish one entity oraction from another entity or action without necessarily requiring orimplying any actual such relationship or order between such entities oractions.

FIG. 1 shows prior art where an intended device for charging as well asa non-intended foreign object are present. Generally, when the wirelesspower transmitting device cannot detect coupled devices power will bedissipated into the foreign object. This dissipated power may betranslated into thermal energy resulting in a loss of efficiency and/ora safety hazard for the system. The system 100 includes a primarytransmitter coil 110 that generates a magnetic field 112 which interactswith an intended secondary receiver coil 114 in a receiving device 116and an unintended foreign object 118.

The instant disclosure describes an array of sensing devices to detectwhat objects are present. Possible sensing techniques comprisecapacitive variation, resistive variation, pressure variation, inductivevariation, and the like. One possible solution is to place sensingdevices within the proximity of the transmitter and the magnetic fieldgenerated beyond the primary transmitter coils.

FIG. 2 shows a wireless power transfer foreign object detector 200comprising at least one foreign object sensor 210 providing at least oneforeign object detection signal 212 to a power transmitting and controldevice 214. At least one primary transmitter coil 216 provides amagnetic field 218 and at least one primary transmitter signal. Thesecondary receiver coil 220 is located in the receiving device. Theprimary transmitter coil is responsive to the at least one foreignobject detection signal through the signals received from the powertransmitting and control device 214. The foreign object detection signalis based at least in part upon the detection of the foreign object 222.

The at least one primary transmitter signal may comprise a data signal.The transmitter mat may be connected to the at least one foreign objectsensor. The at least one foreign object detector may detect a capacitivevariation, a resistive variation, a pressure variation, an inductivevariation, a thermal variation, an image variation, a magnetic orelectric field characteristic or the like, that indicates the presenceof a foreign object.

At least one visual imaging sensor can be used, such as an infra-redsensor or sensor array, or other opto-couplers. These sensors can bearrayed to determine the location of any objects. The objects can beintended devices containing secondary coils, or foreign objects.

Thermocouples can be arrayed in the foreign object detector. Due to theheat generated by objects coupled to the field generated by the primarycoil, any changes and/or thermal gradients detected as a result of thepresence of the thermocouples can indicate the location and placement ofdevices on the detector.

FIG. 3 shows a wireless power transfer foreign object detector 300comprising a transmitter mat 310, at least one foreign object sensor 312connected to the mat and providing at least one foreign object detectionsignal 314 to a power transmitting and control device 316 uponinteraction with at least one foreign object 318, wherein the at leastone foreign object sensor detects at least one of a physical interactionwith the at least one foreign object and an electrical interaction withthe at least one foreign object. The least one primary transmitter coil320 provides at least one primary transmitter signal 322 that generatesa field 324 for transmitting power to a secondary receiving coil 326 ofa receiving device. The primary transmitter coil may also be used todetect the presence of the secondary receiving coil. Power transmittingand control device 316 controls power transmission to the secondarycoil. Power transmitting and control device 316 is responsive to the atleast one foreign object detection signal and controls the primarytransmitter coil in accordance with received foreign object detectionsignals. Such control signals may include one or more corrective actionsignals.

FIG. 4 shows a wireless power transfer foreign object detector 400comprising, a transmitter mat 410, a plurality of foreign object sensors412 coupled to the transmitter mat where the plurality of foreign objectsensors providing at least one foreign object detection signal 414. Theplurality of foreign object sensors are disposed in a grid array. Atleast one primary transmitter coil 416 which generates a field 418 iscoupled to the transmitter mat. Although not depicted, the grid arraymay be disposed only within the region of the field 418. The at leastone primary transmitter coil provides at least one primary transmittersignal. The primary transmitter coil is responsive to the at least oneforeign object detection signal triggered by the foreign object 420. Atleast one secondary receiver coil 422 is electronically responsive tothe at least one primary transmitter coil, the at least one secondaryreceiver coil providing at least one secondary receiver signal. The atleast one secondary receiver signal may have a data signal. The at leastone foreign object sensor detects at least one magnetic or electricfield characteristic that may indicate the presence of a foreign object.

The foreign object detection signal may be responsive to multiplesecondary receiver coils 422, 424. A power transmitting and controldevice 426 may generate a corrective action signal in response to aplurality of secondary receiver coils. The transmitting device maygenerate a system alert in response to said corrective action signal.The at least one primary transmitter coil may be de-energized inresponse to said corrective action signal. Additionally, if more thanone device is detected, the transmitter can take corrective actions toshut down the system and send system alerts, such as error lightindicators, and the like.

FIG. 5 shows a wireless power transfer foreign object detector 500comprising a transmitter mat 510 and a plurality of primary transmittercoils 512, 514 embedded in the transmitter mat. The primary transmittercoils emitting fields 516, 518. The at least one receiver coil 520 iselectronically responsive to the at least one of the plurality ofprimary transmitter coils. The at least one of the plurality of primarytransmitter coils senses at least one magnetic or electric fieldcharacteristic of the at least one secondary receiver coil. This fieldcharacteristic allows differentiation between a secondary receiver coiland a foreign object 522.

FIG. 6 shows a wireless power transfer foreign object detector 600comprising a transmitter mat 610 and a plurality of primary transmittercoils 612, 614 coupled to the transmitter mat. The primary transmittercoils emitting fields 616, 618. The at least one receiver coil 620 iselectronically responsive to the at least one of the plurality ofprimary transmitter coils. The at least one of the plurality of primarytransmitter coils senses at least one magnetic or electric fieldcharacteristic of the at least one secondary receiver coil. This fieldcharacteristic allows differentiation between a secondary receiver coiland a foreign object 622.

FIG. 6 additionally shows at least one foreign object sensor 624 isconnected to the transmitter mat and provides at least one foreignobject detection signal upon interaction with at least one foreignobject. The at least one foreign object sensor detects at least one of aphysical interaction with the at least one foreign object and anelectrical interaction with the at least one foreign object. Atransmitting device 626 is coupled to the at least one foreign objectsensor and the primary transmitter coils.

FIG. 6 shows multiple transmitting coils to aid in the free positioningof the receiving device. In this case, the at least one foreign objectsensors are set in a grid array that can be similarly used to detect thelocation of one or more devices on the transmitter pad. The at least oneforeign object sensors and the magnetic field collapse detection may beused in combination with one another.

Multiple radio transmission transceivers can be utilized. Thetransceiver may be placed adjacent to the one or more primarytransmitter coils and for the detection of changes in radio signalsindicative of the location and number of devices placed on the detector.

Magnetic fields can be generated and monitored in the grid array. Anychanges in the magnetic field efficiency would be indicative of anobject placed on the transmitter. This would indicate the location andnumber of devices placed on the transmitter.

The disclosed of sensors and others sensing methods are illustrative ofapparatus and methods which may be used to detect objects on a wirelessdetector mat. One or more combinations of sensors may be used to providea means to detect objects placed on the transmitter mat. Any type ofwireless transmitter scheme, such as magnetic indication, multiplecoils, mobile movement of transmitter coil or other system methods canuse any or any combination of sensing schemes to detect objects placedon the transmitter.

A method of wireless power transfer foreign object detection 700comprising the steps of, detecting 710 at least one of a physicalinteraction with at least one foreign object and an electricalinteraction with the at least one foreign object and providing at leastone foreign object detection signal. The method comprises the step ofmodulating 712 at least one primary transmitter signal in response tothe at least one foreign object detection signal, wherein the modulationcomprises at least one of reducing the at least one primary transmittersignal and redirecting the at least one primary transmitter signal inresponse to the at least one foreign object detection signal.

The redirection of the at least one primary transmitter signal may be toat least one primary transmitter coil that is not adjacent to the atleast one foreign object. The reduction of the at least one primarytransmitter signal may be to at least one primary transmitter coil thatis adjacent to the at least one foreign object.

A method and description of wireless power transfer foreign objectdetection 800 comprising the steps of, detecting 810 at least onemagnetic or electric field characteristic and comparing 812 the detectedcharacteristic to a magnetic or electric field characteristic look-uptable. The look-up table, also referred to herein as a window, may, forexample, store characteristics of expected or acceptable secondarycoils. If a detected characteristic is not found in the look-up table orwindow, an object is presumed to be foreign. The method furthercomprises modulating 814 at least one primary transmitter signal inresponse to the compared at least one magnetic or electric fieldcharacteristic, wherein the modulation comprises at least one ofreducing the at least one primary transmitter signal and redirecting theat least one primary transmitter signal in response to the at least onemagnetic or electric field characteristic.

While the making and using of various exemplary examples of thedisclosure are discussed herein, it is to be appreciated that thepresent disclosure provides concepts which can be described in a widevariety of specific contexts. It is to be understood that the device andmethod may be practiced with coupled inductor systems havingcommunications and power transfer functionality, such as for example,battery chargers, AC/DC converters, power supplies, and associatedapparatus. For purposes of clarity, detailed descriptions of functions,components, and systems familiar to those skilled in the applicable artsare not included. The methods and apparatus of the disclosure provideone or more advantages including but not limited to, data transfercapabilities, managed power transfer capabilities, and enhanced energyutilization and conservation attributes. While the disclosure has beendescribed with reference to certain illustrative examples, thosedescribed herein are not intended to be construed in a limiting sense.For example, variations or combinations of steps or materials in theexamples shown and described may be used in particular cases while notdeparting from the disclosure. Various modifications and combinations ofthe illustrative examples as well as other advantages and examples willbe apparent to persons skilled in the arts upon reference to thedrawings, description, and claims.

What is claimed is:
 1. A wireless power transfer foreign object detectorcomprising: a transmitter mat; a plurality of foreign object sensorscoupled to said transmitter mat, said plurality of foreign objectsensors providing at least one foreign object detection signal, saidplurality of foreign object sensors disposed in a grid array; aplurality of primary transmitter coils coupled to said transmitter mat,said plurality of primary transmitter coils each providing at least oneprimary transmitter signal, said plurality of primary transmitter coilsresponsive to said at least one foreign object detection signal toredirect the primary transmitter signal in response to the foreignobject detection signal away from at least one of the primarytransmitter coils; a transmitting device that generates a correctiveaction signal in response to said foreign object detection signal; saidtransmitter mat configured to allow placement of at least one secondaryreceiver coil so that it is electrically responsive to at least oneprimary transmitter coil, wherein said at least one secondary receivercoil may provide at least one secondary receiver signal; and whereinsaid plurality of foreign object sensors detects at least one magneticor electric field characteristic of said at least one secondary receivercoil, wherein said foreign object detection signal is responsive to aplurality of secondary receiver coils.
 2. The wireless power transferforeign object detector according to claim 1 wherein said at least onesecondary receiver signal comprises a data signal.
 3. The wireless powertransfer foreign object detector according to claim 1 further comprisinga transmitting device that generates a system alert in response to saidcorrective action signal.
 4. The wireless power transfer foreign objectdetector according to claim 1 wherein at least one primary transmittercoil s de-energized in response to said corrective action signal.
 5. Thewireless power transfer foreign object detector according to claim 1further comprising a transmitting device that generates a system alert.6. The wireless power transfer foreign object detector according toclaim 1 further comprising a transmitting device that is responsive tosaid corrective action signal.
 7. The wireless power transfer foreignobject detector according to claim 1 wherein at least two primarytransmitter coils are de-energized in response to said corrective actionsignal.
 8. The wireless power transfer foreign object detector accordingto claim 1 wherein more than two primary transmitter coils arede-energized in response to said corrective action signal.
 9. Thewireless power transfer foreign object detector according to claim 1wherein at least one foreign object sensor detects at least onecapacitive variation.
 10. The wireless power transfer foreign objectdetector according to claim 1 wherein at least one foreign object sensordetects at least one resistive variation.
 11. The wireless powertransfer foreign object detector according to claim 1 wherein at leastone foreign object sensor detects at least one pressure variation. 12.The wireless power transfer foreign object detector according to claim 1wherein at least one foreign object sensor detects at least oneinductive variation.
 13. The wireless power transfer foreign objectdetector according to claim 1 wherein at least one foreign object sensordetects at least one thermal variation.
 14. The wireless power transferforeign object detector according to claim 1 wherein at least oneforeign object sensor detects at least one image variation.
 15. Thewireless power transfer foreign object detector according to claim 1wherein at least one foreign object sensor detects at least one magneticor electric field characteristic.
 16. The wireless power transferforeign object detector according to claim 1 wherein at least oneprimary transmitter signal is responsive to said at least one foreignobject detection signal.